To improve product yield, pollution control is a. crucial link in a preparation process of a semiconductor integrated circuit or flat-panel display. Before exposure to light, a mask, a silicon wafer, a glass substrate, or the like needs to be subjected to detection of foreign objects, such as foreign particles, fingerprints, scratches, pinholes, etc.
A particle detection device integrated inside a photolithography apparatus generally uses a dark-flied scatterometry technique, of which a detection principle is shown in FIG. 1. Light 101 emitted from a radiation light source 10 is incident on a to-be-detected flat panel 40 at a particular angle, and then is scattered by foreign objects on the to-be-detected flat panel 40. Scattered signal light 102 enters a detection unit 20 right opposite the to-be-detected fiat panel 40. However, the detection device is structurally subjected to particle mirror crosstalk, which becomes severer when the lower surface of the detected flat panel is a chrome mask. In addition, crosstalk of patterns on the lower surface of the flat panel 40 also seriously affects the signal-to-noise ratio (SNR) of a detection signal, thus affecting the detection accuracy. For example, the lower surface of a mask is a chrome layer, and patterns to be exposed to light are formed in the chrome layer. When particles exist on the upper surface of the mask, the chrome layer is equivalent to a mirror, and these particles form virtual images with respect to the chrome layer, which are referred to as mirrored particles. As a result, particle mirror crosstalk occurs, which affects the detection.